将API中的数据存储在变量[Angular]中 [英] Store data from API in variable [Angular]

问题描述

我有一个从API获取数据的服务: https://jsonplaceholder.typicode.com/posts/1

I have a service which gets data from API : https://jsonplaceholder.typicode.com/posts/1

但是我不能在变量中存储数据

but i can not store data in variable

代码:Service.ts

Code : Service.ts

public urlServer : string = "https://jsonplaceholder.typicode.com/posts/1";

public getAllProjectsFromAPI() : Observable<any> {
   return this.http.get( this.urlServer, { responseType: 'json' } ); 
}

Component.ts

Component.ts

constructor( private projects : ProjetsService ) { }

  ngOnInit() {
    this.projects.getAllProjectsFromAPI().subscribe( data => this.test = JSON.stringify( data ) );
    console.log( this.test );
  }

我尝试对var测试控制台，但未定义

I try to console test var and i get undefined

推荐答案

您正在尝试记录尚未计算的值.

Your are trying to log a value which is not yet computed.

// this block is asynchronous
this.projects.getAllProjectsFromAPI().subscribe( 
  data => this.test = JSON.stringify( data )
);
// this line is synchronous
console.log( this.test );

在异步块中执行代码:

this.projects.getAllProjectsFromAPI().subscribe(data => { 
  this.test = JSON.stringify(data);
  console.log(this.test)
});

请注意，我添加了 {} 以便在可观察的回调中执行多行.

Note that I added {} in order to execute multiple lines in the observable callback.

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